1. Field of the Invention
The present invention relates to a magnetic recording medium and a process for producing the same.
2. Description of the Related Art
The magnetic tape as an example of the magnetic recording medium may be classified into the conventional coating type tape obtained by applying a magnetic coating composition comprising magnetic powder dispersed in a binder to a film as a nonmagnetic substrate, and a thin metal film type tape, i.e., an evaporation type tape, obtained by superimposing a magnetic layer of a thin metal film completely free of a binder on a nonmagnetic substrate according to a vacuum evaporation method in which the magnetic metal is deposited on the substrate in a vacuum, and the like.
In recent years, the magnetic recording is oriented toward high density recording. The thin metal film type tape is regarded as providing a promising means for high density recording because no binder is contained in the magnetic layer to allow the density of the magnetic material to be increase
More specifically, a magnetic recording medium, e.g., a thin metal film type tape, having a magnetic layer formed either by wet plating means, such as electroless plating, or by dry plating means, such as vacuum evaporation, sputtering or ion plating, has been proposed. Such a magnetic recording medium has a high packing density of the magnetic material such that it is suitable for high density recording.
The magnetic material for the magnetic layer of the magnetic recording medium of a thin metal film type comprises a magnetic metal, such as a Co--Cr alloy and a Co--Ni alloy. However, Co not only is a rare material which presents a cost problem, but also this material causes environmental pollution. Furthermore, Cr and Ni are not only expensive, but also cause environmental pollution.
By contrast, Fe is free of the above problems, so that it has drawn attention as a magnetic material for use in a magnetic recording medium of the thin metal film type. Thus, although Fe and Ni are thought to be candidates for a non-Co metal magnetic material, Fe is believed to be preferred from the viewpoint of the magnitude of saturation magnetization. However, Fe is more likely to rust than Co, so that the former must be rendered chemically stable.
From this viewpoint, the formation of a magnetic film with Fe.sub.x N has been proposed [see Japanese Patent Publication-A Nos. 236113/1985 and 237219/1988 (published on Oct. 3rd, 1988)]. The magnetic recording medium having a magnetic film composed of Fe.sub.x N is reputed to have desirable magnetic properties and excellent corrosion resistance and high density recording performance. In addition, a Fe-C-N film and other films have been proposed [see, for example, Japanese Patent Publication-A No. 89213/1990 (published on Mar. 29, 1990)]. However, none of the conventional films is satisfactory, and hence an improved film is presently desired in the art.